content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2011, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
   * Other names may be trademarks of their respective owners.]
   *
   * -------------------
   * HeatMapDataset.java
   * -------------------
   * (C) Copyright 2009, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes:
   * --------
   * 28-Jan-2009 : Version 1 (DG);
   *
   */
  
  package org.jfree.data.general;
  
  /**
   * A dataset that represents a rectangular grid of (x, y, z) values.  The x
   * and y values appear at regular intervals in the dataset, while the z-values
   * can take any value (including <code>null</code> for unknown values).
   *
   * @since 1.0.13
   */
  public interface HeatMapDataset {
  
      /**
       * Returns the number of x values across the width of the dataset.  The
       * values are evenly spaced between {@link #getMinimumXValue()} and
       * {@link #getMaximumXValue()}.
       * 
       * @return The number of x-values (always > 0).
       */
      public int getXSampleCount();
  
      /**
       * Returns the number of y values (or samples) for the dataset.  The
       * values are evenly spaced between {@link #getMinimumYValue()} and
       * {@link #getMaximumYValue()}.
       *
       * @return The number of y-values (always > 0).
       */
      public int getYSampleCount();
  
      /**
       * Returns the lowest x-value represented in this dataset.  A requirement
       * of this interface is that this method must never return infinite or
       * Double.NAN values.
       *
       * @return The lowest x-value represented in this dataset.
       */
      public double getMinimumXValue();
  
      /**
       * Returns the highest x-value represented in this dataset.  A requirement
       * of this interface is that this method must never return infinite or
       * Double.NAN values.
       *
       * @return The highest x-value represented in this dataset.
       */
      public double getMaximumXValue();
  
      /**
       * Returns the lowest y-value represented in this dataset.  A requirement
       * of this interface is that this method must never return infinite or
       * Double.NAN values.
       *
       * @return The lowest y-value represented in this dataset.
       */
      public double getMinimumYValue();
  
      /**
       * Returns the highest y-value represented in this dataset.  A requirement
       * of this interface is that this method must never return infinite or
       * Double.NAN values.
       *
       * @return The highest y-value represented in this dataset.
       */
      public double getMaximumYValue();
  
      /**
       * A convenience method that returns the x-value for the given index.
       * 
       * @param xIndex  the xIndex.
       * 
       * @return The x-value.
       */
      public double getXValue(int xIndex);
  
      /**
       * A convenience method that returns the y-value for the given index.
       * 
       * @param yIndex  the yIndex.
       * 
       * @return The y-value.
       */
      public double getYValue(int yIndex);
  
      /**
       * Returns the z-value at the specified sample position in the dataset.
       * For a missing or unknown value, this method should return Double.NAN.
       *
       * @param xIndex  the position of the x sample in the dataset.
       * @param yIndex  the position of the y sample in the dataset.
       *
       * @return The z-value.
       */
      public double getZValue(int xIndex, int yIndex);
  
      /**
       * Returns the z-value at the specified sample position in the dataset.
       * This method can return <code>null</code> to indicate a missing/unknown
       * value.
       * <br><br>
       * Bear in mind that the class implementing this interface may
       * store its data using primitives rather than objects, so calling this
       * method may require a new <code>Number</code> object to be allocated...
       * for this reason, it is generally preferable to use the
       * {@link #getZValue(int, int)} method unless you *know* that the dataset
       * implementation stores the z-values using objects.
       *
       * @param xIndex  the position of the x sample in the dataset.
       * @param yIndex  the position of the y sample in the dataset.
       *
       * @return The z-value (possibly <code>null</code>).
       */
      public Number getZ(int xIndex, int yIndex);
  
  }
  